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Note that this documentation is for the old 5.2 release.
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Placement in NetarchiveSuite software

Every channel is named after the set of application instances that are expected to receive messages sent to it. All channel names are constructed privately in the dk.netarkivet.common.distribute.ChannelID class. To get a channel, you must use one of the public methods in dk.netarkivet.common.distribute.Channels.

Channel Behavior

There are two types of channels used in the JMS protocol:

  • Queue where only one listener takes a message from the channel. For example a queue where a request for doing a harvest is only received by one harvester.
  • Topic where all listeners takes a copy of the message. For example a batch job which has to be executed by all bitarchive applications.

In NetarchiveSuite we use a naming convention that topic channel names include the string "_ALL_" and the suffix "_TOPIC".

Naming Conventions

The structure of channel names is as follows:

<Environment Name>_<ReplicaID>_[<Channel Specifier Prefix>_]<Channel Specifier>[_<Machine>][_<Application Instance>][_TOPIC]
  • Environment Name value must be the same for all channels on all JVMs belonging to a single NetarchiveSuite installation. It identifies the environment for the queue, e.g.: "DEV", "TEST", "RELEASETEST", "CLOVER", "PROD" or initials of developer running personal environment for e.g. sanity tests. It is read from the setting settings.common.environmentName of the NetarchiveSuite installation.
  • ReplicaID Name of the replica (ie the "location" in a distributed system), or COMMON if channel shared by all replicas.

  • Channel Specifier Prefix if present is one of the following:
    • THE - communicate with singleton in the system.
    • THIS - communicate with one uniquely identified instance of a number of distributed listeners.
    • ANY - has all instances listening to the same queue.
    • ALL - is used for topics only, i.e. topics are sent to all listeners on the channel
  • Channel Specifier simply expresses what the channel is used for. By convention this (usually) describes what kind of application should listen on this channel.

Here is a complete list of the channels in an actual realistic distributed NAS system (IP addresses have been anonymised for security reasons).

Channel NameFunction

SystemTest_COMMON_HARVESTER_STATUS_TOPIC

Topic used by the harvesters to call in ready for new jobs (to the HarvestJobManager)

SystemTest_COMMON_HARVESTMONQueue to which harvesters send messages showing crawl progress for display in the GUI
SystemTest_COMMON_HCHAN_VAL_REQ Queue for harvesters to register the harvest channel they are processing jobs from.
SystemTest_COMMON_HCHAN_VAL_RESP Queue for response from the HarvestManager to the Harvesters requesting HarvestChannel registrations.
SystemTest_COMMON_INDEX_SERVER

Queue for sending messages to the IndexServer

SystemTest_COMMON_JOB_PARTIAL_HIGHPRIORITY Queue used to send jobs to the selective harvesters in the highpriority pool.
SystemTest_COMMON_JOB_SNAPSHOT_LOWPRIORITY Queue used for sending jobs to the harvester configured for snapshot harvesting.
SystemTest_COMMON_MONITOR_TOPIC Topic for the monitor registry
SystemTest_COMMON_THE_REPOS

Queue for sending messages to the ArcRepository.

SystemTest_COMMON_THE_SCHED Queue on which HarvestControllers reply with status messages to the HarvestScheduler.
SystemTest_COMMON_THIS_INDEX_CLIENT_xxx_225_xx_140_HCS_SBHIGH_H3

Queue on which a specific HarvestControllerServer listens for responses from the IndexServer

SystemTest_COMMON_THIS_INDEX_CLIENT_xxx_226_xxx_11_HCS_KBHIGH_H3  
SystemTest_COMMON_THIS_REPOS_CLIENT_xxx_225_xx_xxx_HCS_SBHIGH_H3One-per-client queue on which client (in this case a HarvestControllerServer) receives replies from the repository.
SystemTest_COMMON_THIS_REPOS_CLIENT_xxx_226_xxx_xx_WI One-per-client queue on which client (in this case a WaybackIndexer) receives replies from the repository.
SystemTest_COMMON_THIS_REPOS_CLIENT_xxx_226_xxx_11_HCS_KBHIGH_H3  
SystemTest_COMMON_THIS_REPOS_CLIENT_xxx_226_xxx_11_HCS_KBLOW002_H3  
SystemTest_COMMON_THIS_REPOS_CLIENT_xxx_226_xxx_5_IS One-per-client queue on which client (in this case an IndexServer) receives replies from the repository.
SystemTest_COMMON_THIS_REPOS_CLIENT_xxx_226_xxx_5_VP One-per-client queue on which client (in this case a ViewerProxy) receives replies from the repository.
SystemTest_COMMON_THIS_REPOS_CLIENT_xxx_226_xxx_9_HCS_KBLOW001_H3  
SystemTest_CS_THE_CR Queue for sending messages to a specific Checksum replica (the replica named CS).
SystemTest_KB_ALL_BA_TOPIC Topic for broadcasting messages to all bit archives at KB
SystemTest_KB_ANY_BA Queue for sending a message to any one of the bitarchive applications at KB
SystemTest_KB_THE_BAMON  
SystemTest_SB_ALL_BA_TOPIC  
SystemTest_SB_ANY_BA  
SystemTest_SB_THE_BAMONQueue for sending messages to the bitarchive monitor at SB - ie to run batch jobs on the SB replica.

 

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